Position sensor

Abstract

A high-resolution position sensor utilizes a detector having at least one flat magnetic-field-dependent resistor, in stripe form, whose ends are connectable to an output voltage, and a magnetizable device which is moveable relative to the magnetic-field-dependent resistor and has portions transverse to the direction of movement which exhibit alternately different space permeabilities, with the magnetic-field-dependent resistor extending parallel to and at a distance from said portions by the magnetic-field-dependent resistor. The magnetic field dependent resistor displays anisotropy in the longitudinal direction of the stripes. At least in the area of the magnetic-field-dependent resistor the device is magnetized in or opposite the direction of movement.

We claim: 
     
       1. A position sensor comprising a first support, at least one flat, magnetic-field-dependent resistor in stripe form deposited on said support, said resistor having a longitudinal axis and ends connectable to an output voltage, and a magnetizable device which is movable relative to the magnetic-field-dependent resistor and has portions transverse to the direction of movement which exhibit alternately different space permeabilities, with the magnetic-field-dependent resistor extending parallel to and at a distance from said portions, said resistor having a uniaxial anisotropy, with the easy-axis direction being parallel to the longitudinal axis of said stripe. 
     
     
       2. The position sensor of claim 1, wherein at least in the area of the magnetic-field-dependent resistor, the device is magnetized in or opposite the direction of movement. 
     
     
       3. The position sensor of claim 1, wherein the magnetic field dependent resistor is made of ferromagnetic material. 
     
     
       4. The position sensor of claim 1, wherein the magnetic field dependent resistor has a maximum thickness of 0.5 micrometers. 
     
     
       5. The position sensor of claim 1, further comprising another magnetic field dependent resistor, electrically isolated from the at least one magnetic field-dependent resistor disposed adjacent to at least one magnetic field dependent resistor in a line on said support. 
     
     
       6. The position sensor of claim 5 wherein the portions of different space permeability are of equal width and further comprising a second support having two second support magnetic-field-dependent resistors electrically isolated one from the other and from the resistors on said first support, said two second support resistors being arranged parallel one to the other and to the resistors on said first support in such a manner that the resistors on said first support are separated from the resistors on said second support by a distance   A=(2 n+1 )     where     n=0, 1,2, . . .     is the number of said portions of said magnetizable device of different space permeabilities located between the pairs of magnetic-field-dependent resistors.   
     
     
       7. The position sensor according to claim 1 wherein the device contains a stray-field mask comprising the portions of different space permeability. 
     
     
       8. The position sensor according to claim 1 wherein the device is designed in the form of a portion of a rack. 
     
     
       9. The position sensor according to claim 1, wherein the device is designed in the form of a toothed disk. 
     
     
       10. The position sensor according to claim 1 wherein the portions are made of alternate non-magnetic and magnetic materials. 
     
     
       11. The position sensor according to claim 1 wherein the portions of higher space permeability, and the support therefor are made of soft magnetic material which, at least in the area of the magnetic-field-dependent resistors is magnetized in or opposite to the direction of movement by means of a constant magnetic field, and wherein the longitudinal axis of the magnetic-field-dependent resistors is disposed at least almost transverse to the direction of movement and to the surface of the portions. 
     
     
       12. The position sensor according to claim 1, wherein the portions of higher space permeability, and the support therefor are made of hard magnetic material and are magnetized in or opposite the direction of movement. 
     
     
       13. The position sensor according to claim 12 wherein the surfaces of the magnetic-field-dependent resistors extend parallel to the direction of movement and parallel to the surface of the portions. 
     
     
       14. The position sensor according to claim 6 wherein the two pairs of resistors are located on a common support and employed in a bridge circuit, and one magnetic-field-dependent resistor of each pair of resistors is interposed in an arm of the bridge that is diagonally opposite the respective other magnetic-field-dependent resistor. 
     
     
       15. The position sensor according to claim 1, wherein projecting connection pins are disposed on the upper edge of the support(s) which is located opposite the magnetic-field-dependent resistor. 
     
     
       16. The position sensor according to claim 6 wherein said first and second supports are respectively attached on either side each of a mounting plate having a thickness approximately equal to the distance (A). 
     
     
       17. The position sensor according to claim 6, wherein a mounting plate is disposed on the upper edge of the supports with the mounting plate having openings arranged in such a manner as to produce at least an approximation of the distance (A). 
     
     
       18. The position sensor according to claim 1 wherein the support is made of glass. 
     
     
       19. The position sensor according to claim 1 wherein the support ismade of ceramic. 
     
     
       20. The position sensor according to claim 1 wherein said portions of said magnetizable device which exhibit different space permeabilities define a first plane in the vicinity of said support and said flat, magnetic-field-dependent resistor defines a second plane perpendicular to said first plane, whereby the stray-field component H St  at the boundary of two portions of said magnetizable device having different space permeability may be detected.